Effect of shorting posts or vias on stacked U-slot microstrip antenna performance

The presented stacked shorted U-slot microstrip antenna shows a possibility to achieve an wide 2∶1 VSWR bandwidth of 68%, but, with almost dual band gain behaviour separated by frequency 4.20 GHz. The reason for the gain drop has been explained with the help of current plot. The simulated and measured radiation patterns data (Table 1) have shown that antenna exhibits almost stable co-polarization patterns and acceptable broadside cross polarization characteristics except around 4.20 GHz.